At first, the new Mahāyāṇa movement was called Bodhisattvayāṇa, because it was the vehicle of the bodhisattva (yāṇa = vehicle).
This term distinguished these Mahāyāṇa followers from those who aimed to become only arhats and pratyeka-buddhas.
According to early Mahāyāṇa thought, the arahat kind of Buddha (somebody who aims for his own enlightenment) is selfish.